The invention relates in general to power systems and in particular to a power system incorporating redundant, auxiliary power sources to provide high reliability power to critical loads. Electronic data processing (EDP) is an increasingly important part of current business operations. Computers are used in all aspects of modem business including conducting transactions, controlling production and maintaining data. If the computers are rendered inoperative, it can cost certain businesses on the order of millions of dollars per minute.
A known cause of computer failure is an interruption in the computer power source. Computers used for EDP are sensitive to power interruptions and even a brief interruption or fault can cause the computer to malfunction. FIG. 1 is a graph of a Computer Business Equipment Manufacturers Association (CBEMA) curve, which has been adopted by the Institute of Electrical and Electronics Engineers (IEEE) as Standard 446-1987, indicating that a computer can tolerate a one half cycle or 8.3 ms power interruption. Power available from existing utility grids (industrial power) cannot meet the high power reliability requirement of modern computer equipment. A business operating and relying upon electronic data processing equipment cannot rely on industrial power given the numerous and lengthy interruptions. Accordingly, high quality power systems are required.